The present invention relates to a radio pager and, more particularly, to a radio pager capable of selectively displaying one of a plurality of message signals.
With the striking progress in the art of integrated circuits, a radio pager now under development is furnished with various functions other than the simple selection of selective calling (or paging) signals. A known type of such a pager receives, stores and displays a message signal following a selective calling signal. This type of pager is disclosed in U.S. Pat. No. 4,249,165 entitled "Digital Radio Pager," granted to Y. Mori and assigned to the present assignee.
While the Mori radio pager has a memory (or shift register) for storing a single message, the use of additional shift registers will permit the storage of a plurality of messages. In this case, regardless of whether or not the received messages are identical, they will be sequentially stored in the shift registers in the order of reception and, when the entire storage is filled up, erased sequentially from the oldest one. Generally, a system using such a radio pager repeatedly transmits a call including a selective calling signal and a message signal from a transmitting base station to the radio pager in order to increase the probability of reception at the radio pager, which is known as the so-called "repeat call". Upon a repeat call, the radio pager using the shift registers stores the same message repeatedly in its storage while successively erasing useful messages already stored therein, resulting in inconvenience.
Two different methods are available for reading out and confirming stored messages: one in which the pager itself reads the messages automatically without interruption out of a plurality of corresponding storage areas in response to a single actuation of a readout switch and displays the messages on a display unit, and the other in which a readout switch is actuated once for the reading-out of each message, that is, "n" times in total ("n" indicates the number of stored messages).
Though simple in operation, the former needs a long period of time for readout operation with an increase in the number of messages "n". This is not only a waste of time but contradictory to the general demand for lower power consumption. The latter facilitates recognition of the stored data within a shorter period of time than the former even if the number "n" is relatively large, though depending on the person's perception. However, since the number of stored messages is unknown, there is the risk of person's overlooking one full round of the messages unless they are counted up, or of failing to determine which one of the messages is the latest. :The confusion will be particularly troublesome when the same message has been stored repeatedly.